Carl Sagan.Contact.
1985

Carl Sagan.The Demon-Haunted World: science as a candle in the dark.
Headline. 1996

Sagan again appeals for sanity, rationality and scepticism. Not that
dull, unimaginative scepticism that denies anything a little weird:
after all, what is weirder than quantum mechanics? Rather, the
tough-minded scepticism that requires some evidence before it
accepts an idea. He complains that most people, through little fault
of their own, do not have access to the tools of sceptical thought, so
it is little wonder that they can't tell the difference between the
real wonders of the world, and the wondrous claims of pseudoscience.

In the first half of this book Sagan mainly explores UFOs and the
alien abduction phenomenon. He does this by going back through
history, and describing related phenomena -- incubi and succubi, holy
visions, demons, witchcraft, fairies, and more recently ritual satanic
abuse, and false memory syndrome -- and showing that they all have
remarkably similar features, with the main variations explicable by
them being filtered and interpreted through the prevailing cultural
expectations. Might they not then just conceivably be all the same,
human, experience -- of dreams and hallucination, possibly brought on
by mild sensory deprivation (as occurs when lying sleepily in a quiet,
darkened room), or by temporal lobe epilepsy, or implanted (albeit
unknowingly) by therapists? But he does think there is something
worth investigating:

p178.And if the alien abduction accounts are
mainly about brain physiology, hallucinations, distorted memories of
childhood, and hoaxing, don't we have before us a matter of supreme
importance, touching on our limitations, the ease with which we can be
misled and manipulated, the fashioning of our beliefs, and perhaps
even the origins of our religions? There is genuine scientific paydirt
in UFOs and alien abductions - but it is, I think, of a distinctly
home-grown and terrestrial character.

I felt he could have made clearer the reason for requiring hard,
reproducible evidence, rather than relying on anecdotal evidence. The
reason is so crystal clear to him, but it may not be so to everyone.
After all, we would believe a friend who said they had seen a shooting
star: why would we want more if they said they had seen a UFO? Where
do we draw the line? We usually say "extraordinary claims require
extraordinary evidence", but problems arise with this heuristic
when people are awash in a culture that indicates these are not
extraordinary claims.

p200.Appeal to ignorance -- the claim that
whatever has not been proved false must be true, and vice versaa ...
This impatience with ambiguity can be criticized in the phrase:
absence of evidence isn't evidence of absence.

Next, Sagan turns his attention to literacy and education (with
emphasis on the USA), and suggests some ideas on how this might be
improved. I think this is the weakest part of the book, probably
because I have read it all before. These kind of suggestions of how to
improve education to me always seem to miss the point. Yes, in
principle it is possible to implement any of these suggestions
-- they happen in other countries, and happened in the past. But what
is needed in practice is a change of culture, attitude and will -- a
widespread belief that education, from basic literacy right through to
basic research, is vitally important -- and this is much
harder to achieve. At one point I felt I saw where a small difference
in presentation could have had a large difference in outcome: when
discussing the failure of the High Energy Superconductor Supercollider
(SSC) project, possibly because the idea was poorly presented to the
funders.

Finally, he turns to a "problem" with scepticism. Once the
mindset has been learned, sceptics tend to require evidence for everything
-- not just for the existence of UFOs or astrology, but also for the
authoritarian pronouncements of their leaders, be they secular or
religious. This can make sceptics uncomfortable and unpopular people,
but such an approach to life is the only way to guard against error.

There is much here. Sagan's passion for science, his humanity, and
his open-mindedness -- coupled with scepticism, naturally -- leaps
from every page. He shows that science is a marriage of wonder (Here's
a really beautiful idea) and scepticism (Let's see, does it work? Ah,
no. Pity. So, I need another idea). Also, he is careful not to label
New Agers as nutcases, but argues that there is something important
and deeply human about their search for wonder -- they are just using
the wrong tools to find it. My minor quibbles notwithstanding, this is
a cogently argued and wonderfully humane book. Now, how to get the
right people to read it?

Carl Sagan.Billions and Billions: thoughts on life and death at the brink of the millennium.
Headline. 1997

Carl Sagan.The Varieties of Scientific Experience: a personal view of the search for god.
Penguin. 2006

Carl Sagan’s prophetic vision of the tragic resurgence of fundamentalism
and the hope-filled potential of the next great development in human spirituality

The inimitable Carl Sagan sets forth his detailed thoughts on the relationship between religion and science,
and describes his personal search to understand the nature of the sacred in the vastness of the universe.
Exhibiting a breadth of intellect nothing short of astounding,
the late, great astronomer and astrophysicist offers a delightfully intimate discussion of his views on a wide range of topics,
including the likelihood of intelligent life on other planets, creationism and so-called intelligent design,
and a new concept of science as “informed worship.”
Originally presented at the centennial celebration of the famous Gifford Lectures in Scotland in 1985,
this book offers a unique encounter with one of the most remarkable minds of the twentieth century.